1. Field of the Invention
The field of this invention is electric lamps and, in particular, LED (light-emitting diode) lamps.
2. Description of the Prior Art
With reference to FIG. 16, a conventional LED lamp generally comprises a metal rod 91 having two ends and an outer surface. An LED 92 is attached to one end of the metal rod 91. Heat-transferring fins are annularly attached to and radially protrude from the outer surface of the metal rod 91. A base 94 is attached to the other end of the metal rod 91 and leads 96 protrude outward from the base 94 electrically to connect the LED 92 to a power source. A cover 95 overlies the LED 92. The cover 95 alters the illuminating pattern of the LED lamp and protects other structures of the LEDs lamp.
However, the metal rod 91 is not capable of satisfying heat transportation. Heat generated by the LED 92 during operation may not be effectively transferred, which forbids using high-power LED or using multiple LEDs within one LED lamp.
Wither reference to FIG. 17, a conventional LED system using no sintered heat pipe has an LED mounted onto a MCPCB. The MCPCB is attached to a receiving plate of a heat sink. The temperature of the LED itself and the temperatures of the following measurement points are also measured. The measure points include different points T1, T2 of the MCPCB, different points T3, T4 of the receiving plate and fins T5-T9 of the heat sink. The temperature readings are listed in Table 1.
TABLE 1temperature (° C.)InputT1T2T3T4T5T6T7T8T90.5 A * 23.7 V =51.9852.2246.4345.7744.014547.5946.0846.511.85 W0.75 A * 23.9 V =62.6563.4654.4753.5850.552.4156.1653.8754.5317.925 W1 A * 23.9 V = 23.9 W72.0372.6361.5460.3556.3858.763.860.7661.63
With reference to FIG. 18, calculated temperatures of the MCPCB of the LED and the heat sink and the temperature of the LED are further listed in Table 2
TABLE 2temperature (° C.)InputMCPCBHeat sinkLED0.5 A * 23.7 V = 11.85 W52.145.83687.650.75 A * 23.9 V = 17.925 W63.05553.494116.831 A * 23.9 V = 23.9 W73.3360.254144.03
The temperature of the MCPCB is considerably higher than that of the heat sink, which indicates an accumulation of the heat generated by the LED around MCPCB. The phenomenon demonstrates the high heat-transfer resistance of the MCPCB constitutes a proximal heat-transfer resistance in the conventional system that is responsible to the accumulation of heat.
Accordingly, an LED lamp is needed that will mitigate or obviate the aforementioned problems.